Chronic alcohol use puts the compulsive part of your brain in charge, and the changes appear to be physical, not just mental, federal researchers say.

View full sizeLiquor is on display inside A Beer at a Time in Washougal, Wash.,Brent Wojahn, The Oregonian, 2012

Scientists are furthering their understanding of how alcohol gets people hooked while simultaneously interfering with brain function, and hope to use the knowledge to better treat alcoholism.

Chronic alcohol use causes physical changes to the brain that shift behavior control to the habit-forming portion of the brain and away from the pre-frontal cortex involved in complex decision-making, according to a federally funded study of mice.

Mice brains are frequently used to study addiction in humans. In this case, mice regularly exposed to alcohol vapor showed significant changes in the nerve cells of the brain's dorsal striatum, which regulates habit formation and motivation.

The physical changes may affect how the brain's synapses adapt to change over time. They also reduce the activity of the brain receptors believed to play a role in memory, mood and sensation.

Researchers with the National Institutes of Health believe the study shows physical changes that underlie the progression to alcoholism. In effect, control of decision-making shifts from the portion of the brain that provides impulse control and supports rational decision-making, over to the part that fosters habits, compulsive behavior and conditioned response.

The study was published in the Proceedings of the National Academy of Sciences. It was led by Andrew Holmes in the Laboratory of Laboratory of Behavioral and Genomic Neuroscience at N Institute of Alcohol Abuse and Alcoholism, a branch of NIH.